Turbine engine cvc combustion chamber module comprising a pre-combustion chamber

ABSTRACT

A turbine engine combustion chamber module including at least one constant-volume combustion chamber. The module includes, upstream of the at least one constant-volume combustion chamber, a precombustion chamber capable of producing hot combustion gases that supply the at least one constant-volume combustion chamber so as to allow the ignition thereof.

TECHNICAL FIELD

The present invention relates to the field of turbomachines, and more particularly to field of constant-volume combustion type turbomachine combustion chambers.

The invention is applicable to any type of terrestrial or aeronautical turbomachines, and for example to aircraft turbomachines such as turbojet engines and turboprop engines.

More precisely, it is directed to a constant-volume combustion type turbomachine combustion chamber including a pre-combustion chamber, as well as a turbomachine including such a combustion chamber module.

STATE OF PRIOR ART

Conventionally, a turbomachine combustion chamber operates according to the Brayton thermodynamic cycle, with a so-called constant-pressure combustion.

However, for a specific consumption gain, it has been contemplated to replace the Brayton cycle combustion chamber with a Humphrey thermodynamic cycle combustion chamber, with a so-called constant-volume combustion or even “CVC”, implementing an isochoric process.

By way of example, patent application FR 2 945 316 A1 describes making a CVC type combustion chamber. The chamber comprises at the input a compressed gas intake valve able to switch between an open position and a closed position, and includes at the output a burnt gas exhaust valve also able to switch between an open position and a closed position. The positions of the valves are driven in a synchronised way in order to implement the three successive phases of the Humphrey cycle, namely intake-combustion-exhaust.

Since the process implemented is isochoric, the Humphrey cycle implies to preserve the load during some period of time in a physically enclosed volume. This operating mode induces a pulsed regimen. Indeed, the air from the compressor is taken in inside the combustion chamber. Then, after the cams are closed, a spark initiates the combustion in the chamber. Once this combustion is ended, the chamber is opened to let hot gases escape to the turbine in order to produce power, or directly to the nozzle in order to produce aerodynamic pressure.

More specifically, the constant-volume combustion process of a Humphrey cycle combustion chamber requires energy input to each combustion cycle in order to be able to trigger a combustion by propagation of a flame front. In particular, such a combustion requires a significant energy which is repeated over time.

Among the current solutions aiming at feeding the energy necessary for igniting a CVC type combustion chamber, the solution consisting in generating ignition by an electric arc ignition system is known. However, such a solution implies the use of a robust and redundant system. The solution consisting in using burnt gases of a previous combustion cycle or even those of a close or neighbouring combustion chamber is also known. However, such a system is very complex to manage and can downgrade the intrinsic potential of the combustion system. Thus, the current solutions are not entirely satisfactory.

DISCLOSURE OF THE INVENTION

One purpose of the invention is therefore to fulfil at least partially the abovementioned needs and drawbacks related to embodiments of prior art.

In particular, the invention aims at providing an alternative solution of energy input necessary to the ignition of a constant-volume combustion type turbomachine combustion chamber.

One object of the invention, according to one of its aspects, is thus a turbomachine combustion chamber module, including at least one constant-volume combustion type combustion chamber, characterised in that it further includes, upstream of said at least one constant-volume combustion type combustion chamber, a pre-combustion chamber capable of producing hot combustion gases supplying said at least one constant-volume combustion type combustion chamber to allow the ignition thereof.

By virtue of the invention, it can be possible to produce, upstream of the CVC type combustion chamber(s) of a combustion module in accordance with the invention, through a pre-combustion chamber, hot gases feeding the energy necessary to the ignition of the CVC type combustion chamber(s). In particular, the invention can enable a desired capacity to be provided for allowing the ignition of the CVC type combustion chamber(s) under so-called “severe” operating conditions, in particular in case of cold and high altitude. Thus, the invention can make it possible to integrate, on a turbomachine combustion module, a specific system for the thermal ignition of one or more CVC type combustion chambers, so as to limit the engine destabilisation and to optimise the engine efficiency.

The combustion chamber module according to the invention can further include one or more of the following characteristics taken alone or according to any technically possible combinations.

Advantageously, the pre-combustion chamber is of the constant-pressure combustion type, implementing an isobaric process.

Said at least one combustion chamber being of the CVC type, it advantageously includes a compressed gas intake valve able to assume an open position as well as a closed position in which it opposes to the compressed gas intake, and further a burnt gas exhaust valve able to assume an open position as well as a closed position in which it opposes to the exhaust of burnt gas outside the chamber.

On the other hand, preferentially, the pre-combustion chamber is configured to produce predominantly burnt gases of carbon monoxide and dihydrogen.

Further, according to one alternative embodiment, the module according to the invention can include, downstream of the pre-combustion chamber and upstream of said at least one constant-volume combustion type combustion chamber, an oxidation catalyst module, making it possible in particular to increase the dihydrogen rate of the hot combustion gases supplying said at least one constant-volume combustion type combustion chamber to allow the ignition thereof.

Preferentially, the module according to the invention includes a plurality of constant-volume combustion type combustion chambers distributed about an axis of rotation of the turbomachine.

Further, the pre-combustion chamber can supply hot combustion gases to the constant-volume combustion type combustion chambers through a rotary distributor type system.

Besides, one object of the invention is also, according to another of its aspects, to provide a turbomachine, characterised in that it includes a combustion chamber module as previously defined.

The combustion chamber module and the turbomachine according to the invention can include any of the previously set-out characteristics, taken alone or according to any technically possible combinations with other characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention could be better understood upon reading the detailed description that follows, of an exemplary implementation not limiting the same, as well as upon examining schematic and partial Figs. of the appended drawing, in which:

FIG. 1 represents a side schematic view of a turbojet engine gas generator including an exemplary constant-volume combustion type combustion chamber in accordance with the invention, and

FIG. 2 represents a front schematic view of the combustion chamber module of FIG. 1.

Throughout these Figs., identical references can designate identical or analogous elements.

Furthermore, the different parts represented in the Figs. are not necessarily drawn to a uniform scale, to make the Figs. more readable.

DETAILED DISCLOSURE OF A PARTICULAR EMBODIMENT

Throughout the description, it is noted that the terms upstream and downstream are to be considered with respect to a main normal flow direction F of the gases (from upstream to downstream) for a turbomachine. On the other hand, by axis T of the turbomachine, it is meant the radial axis of symmetry of the turbomachine. The axial direction of the turbomachine corresponds to the direction of the axis T of the turbomachine. A radial direction of the turbomachine is a direction perpendicular to the axis T of the turbomachine. Further, unless otherwise mentioned, the adjectives and adverbs axial, radial, axially and radially are used in reference to the aforementioned axial and radial directions.

In reference to FIG. 1, there is represented, in a side schematic view, an exemplary embodiment of an aircraft turbomachine gas generator 1, preferably a turbojet engine, including an exemplary constant-volume combustion CVC type combustion chamber module 4 in accordance with the invention.

The gas generator 1 includes, conventionally, from upstream to downstream, one or more compressor modules 2, a combustion chamber module 4, and one or more turbine modules 3. Usually, the compressor modules 2 and the turbine modules 3 are connected by a shaft system 5, which drives a receiver of the aircraft turbomachine, for example a fan (not represented) in the case of a turbojet engine.

In accordance with the invention, the combustion chamber module 4 includes a plurality of CVC type combustion chambers 7 and, upstream of the same, a pre-combustion chamber 6 capable of producing hot combustion gases supplying the CVC type combustion chambers 7 to allow the ignition thereof.

Advantageously, the pre-combustion chamber 6 is of the constant-pressure combustion type. It produces hot gas jets upstream of the CVC type combustion chambers 7 to feed energy required for the ignition thereof.

The isobaric pre-combustion chamber 6 is quite particularly employed in a rich operation to produce burnt gases predominantly doped with carbon monoxide CO and dihydrogen H₂. In this way, these gases are conducive to the ignition of the main CVC type combustion chambers 7 and favour the reduction in the combustion initiation delay with respect to the use of burnt gases produced with a low CO and H₂ richness.

FIG. 2 represents, in a front schematic view, transverse to the axis of rotation T of the turbomachine, the combustion chamber module 4 of FIG. 1.

As can be seen in this FIG. 2, the plurality of combustion chambers 7 of the CVC type is evenly distributed about the shaft system 5 centred on the engine axis T.

The CVC type combustion chambers 7 are for example provided to be 4, this number being in no way limiting. They all are preferentially identical.

Moreover, the number of these CVC type combustion chambers 7 is preferentially an even number, so as to be able to neutralise two chamber barrels diametrically opposite in case of abnormality on one of them, and thus avoid dissymmetries of flow at the input of the turbine.

Indeed, the CVC type combustion chambers 7 are arranged in a so-called barrel configuration, by being preferably intended to remain fixed with respect to the engine casing upon operating the turbomachine.

Each combustion chamber 7 is of the CVC type, that is closed at its ends by two synchronised intake and exhaust valves in order to implement the three successive phases of the Humphrey cycle, namely intake-combustion-exhaust. Even if they are identical, the CVC type combustion chambers 7 are preferably intentionally phase shifted with respect to each other as regards the implementation of the Humphrey cycle. By way of example, a given chamber which is in an intake phase could be adjacent to another chamber in a combustion phase, and so on.

On the other hand, as can be seen in this FIG. 2, the isobaric pre-combustion chamber 6 supplies hot combustion gases to the CVC type combustion chambers 7 through a rotary distributor type system 8, which enables hot gases to be dispensed to the CVC type combustion chambers 7 as represented by the arrows D in FIG. 2.

Further, although not represented, it is also possible to use, downstream of the pre-combustion chamber 6 and upstream of the CVC type combustion chambers 7, an oxidation catalyst module. This oxidation catalyst is thereby located at the output of the pre-combustion chamber 6 and enables in particular the dihydrogen H₂ rate of the hot combustion gases supplying the CVC type combustion chambers 7 to be increased to allow the ignition thereof. Indeed, a high dihydrogen rate is known to favour the tolerance of a combustion system to the dilution by residual gases. It can be therefore possible to improve the reliability of the entire system which is provided.

Of course, the invention is not limited to the exemplary embodiment just described. Various modifications could be provided thereto by those skilled in the art.

The term “including one” should be understood as being synonymous of “including at least one”, unless otherwise specified. 

1-7. (canceled)
 8. A turbomachine combustion chamber module, comprising: a plurality of constant-volume combustion type combustion chambers distributed about an axis of rotation of the turbomachine, upstream of said plurality of constant-volume combustion type combustion chambers, a pre-combustion chamber capable of producing hot combustion gases supplying said plurality of constant-volume combustion type combustion chamber to allow the ignition thereof, wherein the pre-combustion chamber supplies hot combustion gases to the constant-volume combustion type combustion chambers through a rotary distributor type system.
 9. The module according to claim 8, wherein the pre-combustion chamber is of the constant-pressure combustion type.
 10. The module according to claim 8, wherein the pre-combustion chamber is configured to produce predominantly burnt gases of carbon monoxide and dihydrogen.
 11. The module according to claim 8, further comprising, downstream of the pre-combustion chamber and upstream of said plurality of constant-volume combustion type combustion chambers, an oxidation catalyst module, so to increase the dihydrogen rate of the hot combustion gases supplying said plurality of constant-volume combustion type combustion chambers to allow the ignition thereof.
 12. A turbomachine, including a combustion chamber module according to claim
 8. 